The pedigree shows three siblings with the genotype dd, dd, and dd. did the parents of these three clidren. have the disorder?

If the children had a genetic disorder, the parents would have had to of had the gene. However, the gene could have been recessive (not apparent) in the parents. 

The parents could not have had the disorder. However, the gene was recessive in both parents. To have offspring with each genotype (DD, Dd, and dd), the parents had to be hybrids for the trait. If a punnett square was showing the genes, the top genes would be D and d. The side genes would be D and d also. The upper left box would be DD. The upper right box would be Dd. The lower left box would be Dd. The lower right box would have dd. DD=25% Dd=50% dd=25%