Because of DNA.
sometimes the children dont look like their parents, but they look like other people from their families!
sometimes people dont look like there parents but get there looks from other people in the family such as grand parents uncles and aunts it just happens
my little brother looks like my uncle lol
b/c most likley when they married they only looked at the out side not what truly matters and now they have to learn to love sum thats not to atractive
DNA is not quite that simplistic... you have several alleles, and while they may be expressed in the parents, the child may not express the same alleles... odds are if both parents have attractive features the child will too, but they may get unlucky and express the not so attractive features...
because the parents are brother and sister : p
sometimes you can get the attractive features of your family, or the not so attractive ones.
like my dad has long legs, my mums are short.
mine are long, but they could be short.
if someones mums entire family has a big nose, and only their dad has a small nose in his family, then chances are their kid'll have bigger noses... because it's a more dominant gene. like most people with only one african parents still have darker skin.
it's all DNA...
I hope that helps...
Some traits are more attractive than others...
That doesnt mean that the more you have the more better looking you'll be...
think mom an dads good features... put 'em together in your mind... what do ya got? Probably not that good of an image(unless your lucky and god dealt ya a good hand)