Twins share the same genes, but siblings born at different time does not share the same genes.
Answer: Option D) 8 segments, with the 2 original strands on different segments
Explanation:
During polymerase chain reaction, a double stranded DNA (dsDNA) is selectively and repeatedly copied in the PCR machine.
In the first round, the single piece of double stranded DNA (dsDNA) unwinds in two seperate strands, before complementary nucleotides are synthesized to establish double helix.
In the second round, the two dsDNA yields 4 segments before complementary nucleotides are synthesized to establish double helix.
In the third round, the four dsDNA yields 8 segments before complementary nucleotides are synthesized to establish double helix.
Thus, after 3 rounds, the two original strands are on the 8 different segments of copied DNA.
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!