Why Do Offspring Not Resemble Their Parents

One of the most important reasons that offspring normally do not resemble their parents exactly is because of the passing down of recessive traits from parents to offspring. One reason that recessive alleles cause offspring to differ from their parents is shown an experiment conducted by Gregor Mendel. In this experiment, Mendel crossed a purebred tall plant with a purebred short plant. The resulting offspring, or the first filial generation, was entirely tall. The first filial generation was allowed to self-pollinate, and the second filial generation, to Mendel’s surprise was approximately one-fourth short and three-fourths tall. Another way that recessive alleles can cause offspring to have a physical appearance unlike that of its parents is when one parent has a heterozygous genotype and the other has a homozygous recessive …show more content…
The offspring will either be heterozygous and will inherit the dominant trait from one parent and the recessive from the other, or it will inherit a recessive allele from both parents. The third way that recessive alleles can cause offspring to vary physically from its parents is when recessive alleles are so numerous that they eventually cause the dominant allele to disappear. Suppose two heterozygous pea plants, both with round seeds (Rr), where the allele for round seeds (R) is dominant over the allele for wrinkled seeds (r), were crossed and that an offspring with wrinkled seeds (rr) was created. If this offspring were to be bred with another with the same genotype (rr), all of their offspring would have wrinkled seeds. This would mean that the dominant allele for round seeds has disappeared. In Mendel’s experiment, two purebred pea plants, one tall (TT), the other short (tt), were crossed. The first generation’s genotype was the same for all offspring