The molecule found inside cells that carry the genetic material necessary for an organism to develop and function. This knowledge can be passed on from one generation to the next thanks to DNA molecules.
Recombination causes variation in the DNA of siblings. Meiosis produces sperm and eggs.
Variation occurs during meiosis as a result of crossing over and recombination.
Siblings do share DNA, although on average they only have a 50% (2,600 centimorgans) similarity.