Normal parent with 2 siblings having osteogenesis imperfecta. Pattern of inheritance is

D i.e. Germline mosacism Differential expression of same gene depending on parent of origin is referred to as genomic imprinting. Germline (Gonadal) mosaicism results from a mutation only affecting cells destined to form gonads - postzygotically during early embryonic development. So the individual (parent) is phenotypically normal but can transmit the disease to offsprings through mutant gametesQ. And because the progenitor cells of gametes carry mutation, there is a high possibility that more than 1 child of such parent would be affected.