Did you know that you and your lover are capable of generating more than 70 trillion unique individuals between you? This diversity is generated by combining a randomly chosen half of your 46 chromosomes—the strings of DNA and protein that make you the person you are—with a randomly chosen half of your partner’s 46 chromosomes, for a multiplicity of possible arrangements.
Only not quite randomly. The individual you conceive between you must have 23 matching chromosome sets to be a normal, healthy individual. So a chromosome 1 from Mom is paired with a chromosome 1 from Dad, and so on for a full set of 23 pairs. The two chromosomes in a chromosome set are basically the same, but with variations in some of their genes (and there are thousands of genes in each chromosome). These variations make up the huge diversity we see when we look at people around us.
Since each parent contributes only 1/2 of their child’s set of chromosomes, the chromosome 1 contributed by Mom could have come to her from her own mom or from her dad, since both contributed to her genes. And the chromosome 1 contributed by Dad could have come from either one of his parents. Chromosome 2 could have contributions from an entirely different set of grandparents, and Chromosome 3 could have yet a different mix. There are an astounding 70 trillion possible arrangements for the 23 chromosome pairs.
Add to that complexity a genetic mechanism called cross over, when each person’s chromosome pairs exchange same-yet-different genes between themselves very early in the sexual reproduction cycle, before fertilization ever happens. Because of cross-over, brand new chromosomes never before seen on the face of this earth (or so says my biology teacher) are formed even before mating begins.
This means, with cross over figured in, that you and your lover can generate not just 70 trillion genetically unique individuals (small number that!) but an almost limitless amount.
From this limitless variety that could have been generated by your parents, you were born. And from the limitless variety that could be generated by you and your lover, your child is conceived.
It gives a whole new sense to the meaning of special.
*The information in this post was taken from my biology textbook, Human Genetics: Concepts and Applications, by Ricki Lewis.