In sexual reproduction, what fraction of genes does each parent contribute to the offspring? 1/2
3/4
1/3
1/4

1/2

Explanation:

Well it's like you get 23 chromosomes from each parent. 23 from your dad, and 23 from your mom. In total that's 48 chromosomes, which 23 pairs of chromosmes. Have you ever seen those DNA testing kit commercials for "23 and me" yeah that's based off of the fact that every body has 23 chromosomes. Anyways the main thing is that each parent contributes 1/2 of genes to the offspring.  

i'd say that the moon rock is about 2.2 billion years old.