Final answer:
Whether a child looks more like the mother or father is determined by genetics, where the child inherits a combination of genes from both parents. The sеx of the child is decided by the father's sperm carrying either an X or Y chromosome. Resemblance to either parent is influenced by the variable expression of a blend of maternal and paternal DNA.
Step-by-step explanation:
Whether a baby looks more like the mother or father is a reflection of the complex nature of genetics. Genetics is the branch of biology that deals with heredity and variation in organisms, explaining why children inherit some characteristics from each parent. The traits that a child inherits are determined by the unique combination of genes that are passed down from the mother's egg cell and the father's sperm cell. Each parent contributes approximately 50% of their genes to their offspring, which include a mix of dominant and recessive genes influencing the child's appearance.
To establish a child's relationship to their parents, we look for a DNA fingerprint that includes markers from both the mother and the father. This genetic evidence is definitive proof of biological relatedness. Remarkably, the sеx of the child is determined solely by the father's contribution of either an X or Y chromosome; an XX combination results in a female child, while an XY combination results in a male child. The father has an equal chance of passing on either chromosome to the offspring, leading to a 50:50 chance of the child being male or female.
Perception of resemblance to the mother or father can be subjective and influenced by social dynamics. Yet, it's the blending of maternal and paternal DNA that creates the unique physical characteristics seen in children. While the exact mix and expression of these genes can be quite variable, it can lead to a child looking more like one parent than the other, or a blend of both.