Whenever we inform parents, it is “genetic”, very first reaction of parents who have a child with genetic disorder is — how this happened? We have no family history. While it is true that heredity plays a role, in reality, around 80% of the parents come to know about genetic disorder after the birth of an affected child. All of us have 23pairs of chromosomes which carry Rs 20,000 genes and we get two working copies of every gene from either parent. There are several mechanisms of genetic disorders in the absence of family history. These can be:Spontaneous changes in a chromosomes or genes: Sometimes, defect arise in the chromosomes or genes before or after fertilization in normal parents eg. Down syndrome, William’s syndrome, Marfan syndrome.If parents of carrier of certain genetic conditions: If parents are carriers (carrying one defected copy and other normal copy) they will be normal themselves but can transfer defected copy of genes to their babies. Commonest examples are: Thalassemia, Cystic fibrosis, Spinal muscular atrophy, Fragile X syndrome etc.Conclusion: Genetic disorders can happen irrespective of family history and a proper Preconceptional planning and carrier screening of prospective couple can unmask and prevent them in future children.Dr. Sangeeta KhatterSenior Consultant – Medical & Reproductive Genetics at Jindal IVF, SCO 21, Sector 20-D, Dakshin Marg, Chandigarh, who can be contacted at 958-246-9429.Disclaimer: The views/suggestion/opinions expressed in the article are the sole responsibility of the experts.