Prenatal development is influenced by genes and chromosomes from both parents that are passed down during conception. The zygote contains the genetic material from both the egg and sperm that will determine the traits of the developing fetus. Multiple factors can threaten healthy prenatal growth, including teratogens, the mother's health and lifestyle during pregnancy, and environmental influences. Genetics and environment both play a role in shaping development, personality, and risk of psychological disorders.

1. Prenatal Development