Who do you look like? DNA and family resemblance across generations

Who do you look like? DNA and family resemblance across generations

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It’s a source of wonder how DNA can program people’s faces to resemble others sharing genetic kinship.



Resemblance is the basis of our perception of race and ethnicity.  It is also a favourite topic of conversation at family gatherings – proclaimed where it is strikingly apparent, or perhaps whispered where it is lacking.  Families generally like it when their male biological offspring look like their fathers and females look like their mothers, perhaps with the odd feature thrown in to mark the other half’s creative stamp (“He’s the spitting image of you, but he’s got my eyes”).  Some may start life looking like one parent, then ‘morph’ into the other as they get older.  Certain facial features may perpetuate for generations, or, fascinatingly, even skip generations.  What family historian hasn’t felt a thrill when they unearth an old photograph of a long forgotten ancestor with a distinct family resemblance?  DNA never forgets.

Does the actual percentage of DNA we share have any bearing on our degree of resemblance to each other?  It’s a genetic lottery, of course.  Here are some interesting examples of resemblance across generations:

Resemblance is inevitable with monozygotic (identical) twins who share 99.99% of their genes.  Film aficionados will know that the producers of Terminator 2 kept their special effects budget down by using Linda Hamilton’s identical twin Leslie in certain shots.  The film also featured identical twins Don and Dan Stanton (male monozygotic twins are less common than female).

Monozygotic twins - Linda and Leslie Hamilton, Don and Dan Stanton

 

More commonly, twins will be dizygotic (non-identical) and around half are male-female pairs.  They may share up to around 75% of their genes and, like any other siblings, may look similar, particularly given that they are the same age.

Dizygotic twins - Kiefer and Rachel Sutherland
Dizygotic twins – Kiefer and Rachel Sutherland

 

However, dizygotic twins may also look very different from each other.  Kian and Remee Hodgson were born a minute apart to mixed race parents.  The odds, however, of a mixed race couple having twins of such markedly different colours are very rare.

Dizygotic twins Kian and Remee Hodgson were born a minute apart to mixed race parents.
Dizygotic twins Kian and Remee Hodgson were born a minute apart to mixed race parents.

 

Siblings share 50% of their genes.  While each sibling receives the same genetic material from each parent, the combination of those genes will be different each time, resulting in both physical difference and similarities too.  Some genetic traits will always show up because of their dominance.  Some may even skip generations.

This is evident in the immediate descendants of 10th US President John Tyler.  His grandsons, Lyon Gardiner Tyler Jr. and Harrison Ruffin Tyler, are brothers who only share a passing resemblance.  Harrison strongly resembles his father, Lyon Sr., while Lyon Jr. strongly resembles his grandfather, John.  The Tyler family is remarkable because of the length of time spanning each generation, but this delayed time gap has no effect on their DNA programming – John Tyler’s dominant genes are still showing up faithfully in his grandson over 220 years after his birth.

The Tyler family tree

 

Nobody could mistake the 50% genetic similarity shared by father and son John and Julian Lennon, and the dominance of John’s genes.  Of course, the similar clothes and hairstyle invite comparison.

John and Julian Lennon
John and Julian Lennon

 

Adolf Hitler’s 50% share of his mother’s genes are more apparent as a younger man.  With added weight and years, his father’s genetic traits seem to come to the fore.

Klara, Adolf and Alois Hitler
Klara, Adolf and Alois Hitler

 

Going back a generation, grandparents share 25% genetic similarity with their grandchildren.  The dominant genes of Joseph Stalin and Eleanor Roosevelt are clear in the faces of their respective grandson and granddaughter – Yevgeny Dzhugashvili and Anna Roosevelt.

Joseph Stalin and grandson Yevgeny Dzhugashvili; Eleanor Roosevelt and granddaughter Anna Roosevelt
Joseph Stalin and grandson Yevgeny Dzhugashvili; Eleanor Roosevelt and granddaughter Anna Roosevelt

 

By the time we go back 5 generations, the genetic similarity shared with a particular ancestor is diluted to around 3%.  Actor Skandar Keynes is a great-great-great grandson of Charles Darwin.  He may not grow to share his ancestor’s distinctive looks in old age, but as young children the resemblance is clearly evident.

Charles Darwin and 3 x great grandson Skandar Keynes - as men and boys
Charles Darwin and 3 x great grandson Skandar Keynes – as men and boys

 

Another example of a 5 generation gap is Prince William and his great-great-great grandfather King Edward VII.  Depending on camera angle and facial expression, William can look like any number of his ancestors – but when he briefly sported a beard recently and was snapped in Victorian ‘non-smiling’ mode, he bore a striking resemblance to 19th century playboy Edward, ‘the Uncle of Europe’, particularly around the eyes and the nose.

Prince William and King Edward VII
Prince William and King Edward VII

After 1,000 years of ‘selective breeding’ by the royal families of Europe, the genetic similarity between William and Edward may be somewhat more than the 3% expected in a 5 generation gap.  For example, William’s grandparents – Queen Elizabeth II and her husband Prince Philip – are 3rd cousins from both being directly descended from Queen Victoria, as well as 2nd cousins once removed from their direct descent from King Christian IX of Denmark.

However, things are looking up for William genetically.  At 6ft 3in, he not only towers over the 5ft 5in Edward VII, but he is also set to be the tallest ever monarch in British history (taller even than Edward I, the famed 6ft 2in ‘Longshanks’ who reigned 1272-1307).  Both William and his 6ft 2in brother Harry are the beneficiaries of their father Prince Charles’ genetic masterstroke – to inject the royal bloodline with ‘tall genes’ from the Spencer family.

 

The historic nemesis of British royalty, Oliver Cromwell (who signed King Charles I’s death warrant in 1649), is pictured here alongside his 9 x great-grandson Charlie Bush.  Charlie’s resemblance to his famous ancestor probably owes more to the make-up, wig and costume involved in this fun piece of living history than to his DNA – after 11 generations they will likely share less than 0.05% of their genetic material.  Nonetheless, the resemblance is quite convincing.

Charlie Bush and his 9 x great grandfather Oliver Cromwell
Charlie Bush and his 9 x great grandfather Oliver Cromwell

 

Family resemblances are not only confined to siblings and direct ancestors.  Cousins obviously share genetic material too.  A first cousin will share them same proportion of DNA with you as a great-grandparent (12.5%), and some uncanny resemblances can occur between seemingly distant cousins.  Ralph C Lincoln discovered he shared an ancestor with 16th US President Abraham Lincoln that made them 3rd cousins.  While Ralph has contrived to grow a similar style of beard as Abraham, a split image of their faces reveals an uncanny resemblance.

Abraham Lincoln and his 3rd cousin Ralph Lincoln
Abraham Lincoln and his 3rd cousin Ralph Lincoln

 

And finally, fans of the TV genealogy show Who Do You Think You Are? may recall the first UK series which featured Jeremy Clarkson (still my favourite ever episode).  He uncovered an old photo of his long-dead 1st cousin 3 times removed, George Kilner, which looked startlingly similar to a 1970s passport mugshot of a teenage Clarkson.  Jeremy and George share just 1.56% of their genetic material.

Jeremy Clarkson and his 1st cousin 3 x removed George Kilner
Jeremy Clarkson and his 1st cousin 3 x removed George Kilner

 

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