Will mark ! 30 in snails, the shell may either coil to the right or the left. coiling to the right is dominant. a homozygous recessive female snail is crossed with a homozygous dominant male snail. all of the offspring have shells that coil to the left. why do all of the offspring have left-coiled shells? a this trait follows a typical mendelian pattern of inheritance. b only the father's genotype determines the phenotype for shell coiling. c only the mother's genotype determines the phenotype for shell coiling. d shell-coiling is a sex-linked trait.