If parents contribute different versions of a gene, then the offspring are ______ for that gene.

The correct term to fill in the blank is "heterozygous."

When parents contribute different alleles (versions) of a gene to their offspring, the offspring inherit one allele from each parent. If the two alleles are different, this results in a heterozygous genotype for that particular gene. In contrast, if both alleles contributed are the same, the offspring would be described as "homozygous" for that gene.

In genetics, alleles can be dominant or recessive, and heterozygosity can lead to different traits being expressed in the offspring compared to homozygosity, where traits are often predictable based on the dominant allele present. This genetic variation due to heterozygosity is important for evolution and adaptation in populations.