should missing data be returned as NA (FALSE) or FALSE (TRUE)
Details
This function was designed to identify heterozygous positions in a matrix of genotypes.
The matrix of genotypes can be created with extract.gt.
Because the goal was to identify heterozygotes it may be reasonable to ignore missing values by setting na_is_false to TRUE so that the resulting matrix will consist of only TRUE and FALSE.
In order to preserve missing data as missing na_is_false can be set to FALSE where if at least one allele is missing NA is returned.