Frequently Asked Questions

Heritability is a statistical estimate of how much differences between people in a population are related to genetic differences rather than environmental factors. It does not mean that a condition is determined by genes alone. It does not apply to a single individual. It does not mean something cannot change. A condition can be highly heritable and still influenced by environment and support.

No. Genetic risk increases the likelihood of an outcome; it does not guarantee it. Most common neurodevelopmental and psychiatric conditions are influenced by many genes and by environmental factors. Outcomes reflect probabilities, not certainties.

Even though identical twins may share all of their DNA, it is possible that they are not identical in every way. Differences can arise from differences in the womb (also called “developmental noise”), small biological variations during early development, and unique life experiences.

Genes influence vulnerability, but environment influences how that vulnerability unfolds. Supportive caregiving, early intervention, education, stress reduction, and access to healthcare can shape developmental outcomes. While lifestyle cannot change someone’s genetic makeup, it can influence functioning, coping, and quality of life. Genetic influence does not remove the importance of support and context.