Question about human genetics and the law of independent assortment:?

Question

if the children had two heterozygous parents, how do you use the law of independent assortment to explain why there were no identical twins produced?

Answer 1

Good question. I'll get back to you on that. Otherwise, try GOOGLE! Or before school starts ask some teacher.

Sorry, but that's all I have...

Answer 2

Heterozygous parents produce a lot of different kinds of gametes. If you consider just two traits, so the parent is AaBb, then the possible gametes are AB, Ab, aB, ab. Put these on a Punnett square with similar gametes on the other side, and you have to have a 4 x 4 square with 16 answers.

If you consider the thousands of genes in a gamete, the Punnett squares get bigger and bigger. For three traits, the parent is AaBbCc, and the possible gametes are ABC, ABc, AbC, Abc, aBC, aBc, abC, abc. So the Punnett square is 8 x 8 with 64 answers.

Independent assortment says that the way one pair of alleles (forms of a gene) separates does not affect the way another pair of alleles separates. It's all by chance. So the chances of having identical gametes formed is almost nonexistent, and the chances of identical gametes formed in two parents and joining is practically zero.

Identical twins are actually from one zygote. The embryo comes apart at some point, and the two pieces continue to develop into separate individuals.