The genotype of the short-haired parents that produced some long hair offsprings is probably heterozygous.
<h3>What is heterozygosity?</h3>
Heterozygous means an organism which has two different alleles of a given gene.
An organism that is heterozygous posseses two different alleles of the same gene. For example, in this gene coding for hair length;
L represents short hair (dominant)
l represents long hair (recessive)
Therefore, if two short-haired parents produce 100 offsprings and 25 of them are long-haired, it means that they were probably heterozygous for the short hair.