Meiosis and crossing over?

Question

Under what circumstances would crossing over during meiosis NOT contribute to genetic variation among daughter cells?

Please give me an easy explanation. I am having a hard time understanding this

Answer 1

Crossing over between two sister chromatids would not contribute to genetic variation.  It happens, but is not detected during standard genetic tests.

Also, if there is a lot of homozygosity in the organism, crossing over between non-sister chromatids possibly could  result in no genetic variation.

The best way to learn this stuff is to make diagrams, using labels along the chromosomes such as A, B, C etc.  It is not the easiest way, but in the long run you get a better understanding of meiosis.  For a brief review of meiosis, follow this link.

http://oak.cats.ohiou.edu/~braselto/meio...