Question

Observing Similarities and Differences in Phenotypes Among Family Members

why most family have obvious similarities in physical characteristics and behavior for several children and parents whom you know well (for example, height, weight, eye, and hair color, personality, interests, hobbies). and why sometimes one child shows combined features of both parents, another resembles just one parent, or another is unlike either parent?

Answer 1

There are two major events in sexually reproducing organisms.
1. Meiosis
2. Fertilization

Meiosis is the reductional division. It produces four genetically distinct cells. They differ from each other and from their parent cells. They produce genetic variation by two mechanisms.
i. Independent assortment of chromosomes
ii. Crossing over between non-sister chromatids of the homologous pair

Meiosis produces haploid gametes. Fertilization involves the fusion of gametes to produce a diploid zygote. The zygote undergoes a mitotic division to produce an embryo. The embryo undergoes division and patterning events to produce the adult body.

If parents contain the same alleles for a given gene, the progeny exhibits the same phenotype.
If parents contain two different alleles for a given gene, the progeny exhibits the dominant phenotype.
So, the progeny phenotype depends upon the genotypes of the parents and the allelic combinations that they receive.