If I have hnpcc, does this mean my children will as well?

50% chance. Hnpcc or lynch syndrome is passed on in an autosomal dominant fashion -- this means that your children have a 50% chance of inheriting the defective gene causing the syndrome.
50% chance. In hereditary nonpolyposis colorectal cancer (HNPCC), cancer RISK has an autosomal dominant pattern meaning one inherited copy of the altered gene in each cell is sufficient to increase cancer risk. Any child you have has a 50% chance of inheriting the HNPCC gene. People with HNPCC inherit an increased risk of cancer, not the disease itself, not everyone who inherits the gene will develop cancer.