My sister says she has lactose intolerance. are family members more likely to get the same thing?

GeneticMalabsorption: Defects in lactose absorption can be acquired (due to inflammatory conditions of the intestine) or congenital. Adult lactase deficiency (hypolactasia) is autosomal recessive (ar) & present in >75% of non-caucasians & 20% of caucasians. Congenital lactase deficiency (ar) is acute watery diarrhea in infants. Congenital lactose intolerance (autosomal dominant) can affect liver, kidney, brain, & eyes.

Yes: Lactose intolerance is genetic. So if your sister has it, you are more likely to have it.