why would a person who inherits an allele for curly hair and allele for straight hair have curly hair?

Answer 1

Because the curly gene allele is dominant.

Answer 2

The simple answer is that the curly hair allele is dominant over the straight hair allele.

It's important, though, to understand that there are possible reasons why one allele may appear dominant. For example (and this is only hypothetical), it may be that the curly hair allele produces a regulatory protein that triggers curly hair. If the amount someone with two curly alleles produces is 100%, it may be that someone only requires 30% of this amount to have curly hair, and the rest is overkill. Thus, someone who is heterozygous and makes 50% of the amount, will still appear identical.

A converse by different mechanism would be if it was the STRAIGHT hair allele that makes straight hair, but you need 75% of the amount of a homozygous straight allele to get straight hair. Thus, a heterozygous person who only makes 50% of the amount will not have enough to produce straight hair.

Answer 3

If the allele for curly hair is dominant (I'm not sure it is) then having one allele for curly hair will make the person have curly hair. If the straight hair allele is recessive, then the person will only have straight hair if both the alleles are the recessive straight allele.

Answer 4

Actually, curly hair is not dominant. Normally, a person who has one allele for curly hair and one for straight hair would have wavy hair. Because this gene is humans is a case of incomplete or co-dominance, the person who has one gene for each shows a combination of both traits (like a tulip that has one gene for red flowers and one gene for white flowers actually produces pink flowers).

Answer 5

Pretty much everyone is correct, but you have to take into account that it might be a different type of inheritance and also that you recieve many alleles, not just two.

Answer 6

Because curly hair is dominant over straight hair.

Answer 7

curly is dominant