Explain how the lethal allele is still showing up in the population

Lethal alleles (also referred to as lethal genes or lethal) are alleles that cause the death of the organism that carry them. They are usually a result of mutations in genes that are essential to growth or development. Lethal alleles may be recessive, dominant, or conditional depending on the gene or genes involved. Lethal alleles can cause death of an organism prenatally or any time after birth, though they commonly manifest early in develop