I think that iwantperfection is quite right actually. I think it's VERY easy to spot in most young kids who will have balding trouble.
Everytime I see kindergarten kids get picked up or something, you see a father who is bald picking up his son, his son will definitely have thin and flat hair, probably with thinner hair at the temples as well.
While a father with thick nice hair picking up his son, you will always see that the son will have ridiculously great thick hair. I can spot in no time if a young boy's father is bald or if his father has great hair.