S R NAIDOO
Yes.  Now if you look at it, that would be correct simply because there's a constant and repetitive phenotype that we call the phenotype, the outward expression of a genetic makeup in the family.  What would - biologically or mathematically speaking, both would represent, a child and a sibling could represent, possibly, similar deviations or shall we say, a similar amount of phenotypic outward expression of genetic makeup, simply because the child for example, would be a product of the mother and an external(?) father, whilst a sibling could, there's a possibility, could receive the gene that was not present in Ntombi Kubheka, but present in a sister.  However, simply because there seems to be some constancy in that most of the siblings, or for that matter all of them are shorter than normal.  So what it shows as a probability is that both the mother and father in the Kubheka family, of all the siblings, had shortness as their genetic genotype.  DNA makeup.