How to create new process as its own parent process?

How does the process work by which certain genetic information from each parent are combined into the unique genetic information of a child?

• Certain traits from each parent are passed to a child while others are not. One child inherits a different combination of traits than its sibling. How does the selection and recombination of genetic information work on a chromosome/DNA level in sexual reproduction? Is this process completely random or is it biased in some way to ensure the selection of "better" traits?

• Answer:

  As far as we know, it is generally random. Favorable and unfavorable traits have equal probabilities of being passed on from one parent to one offspring, but unfavorable traits make it less likely that the parent has offspring (or perhaps less likely for the offspring to reproduce, or some other similar variant). As Jacobo says in the comments, there are some processes, such as meiotic drive, that make it more likely for one trait to be passed on to offspring than another, but that may happen to favorable as well as unfavorable traits. Humans have 46 chromosomes, of which 23 (including the Y chromosome in men and one X chromosome in women) come from the sperm (i.e., the father) and 23 (including an X chromosome for both sexes) come from the egg (i.e., the mother). In addition, we inherit mitochondrial DNA from our mothers. Eggs and sperm thus have only 23 chromosomes, but they derive from normal human cells with 46 chromosomes, which form 23 pairs, each consisting of one chromosome from the mother and one from the father. The chromosome number is halved in a process called meiosis, which produces four 23-chromosome from one 46-chromosome one. During this process, all chromosomes are duplicated, the members of each chromosome pair align with each other, then split into two daughter cells that both contain 23 doubled chromosomes. Last, the two daughter cells split into two cells, each containing 23 non-doubled chromosomes. However, during this process a phenomenon named crossing over happens: within one chromosome pair, pieces of chromosomes are exchanged between different chromosomes. This means that the chromosomes we get are almost never exactly those our parents got from their grandparents, but rather mosaics that derive from both of our parents' parents.