Shell coiling in the hermaphroditic snail Limnaea peregra may be right-handed (dextral) or left-handed (sinistral).
The coiling depends on the genotype of egg donor parent, regardless of the phenotype of that parent.

• If that parent is DD or Dd, the offspring will be dextral.
  • The dominant allele (D) produces a gene product that influences spindle orientation in the first cleavage division of the zygote, which in turn affects subsequent cell divisions to produce permanent coiling in that direction.