If the doctor has brown hair with hazel eyes; then how if there were no other parent did he end up with a blonde hair blue eyed daughter? [seems Mehr of a Hollywood Bewegen then a BBC one to me]

It's easy to explain. It's possible because of genetics: 10th has hazel eyes(A) and brown hair(B) and Jenny has blue eyes (a) and blonde hair (b)

Aa + Aa = Aa/AA/aA/aa
Bb + Bb = Bb/BB/bB/bb

That's the way it's explained, because 10th has in his genes his eyes and hair's colour as a dominant character but he's got non-dominant characters (Jenny's hair and eyes' colour) that could be seen if they are recombined with others in the "fertilization".


It could be a little confusing but if you've got science classes Du can know something about it.

As viciouscreature pointed out, both brown eyes and brown hair are dominant characteristics, meaning that someone with those colourings could have recessive blue/blonde genes.

Also, casting availability and the ability to play the part well is Mehr important than appearance in all acting, not just Hollywood.

This is just a thought but maybe the Doctor was born blond and blued eyed so Jenny's looks come from his original appearance before he had his first regeneration. :)