This can be because of their genetics. The siblings may not have inherited their parents looks, but maybe they inherited their grandparents looks, or even their aunts looks. This is all due to genetics. It's sort of the same thing, when two caucasian parents have an african-american child. That would be because somewhere along the family tree someone was african-american.
Anyways, I hope this helps!
Answer:
I think it would be like how the earth formed and other planets except way smaller but I'm not sure
I would say D) all of the above.
65 million years, if I remember correctly
