Childhood Stress Leaves Genetic Scars
sciencehabit writes "Traumatic experiences in early life can leave emotional scars. But a new study suggests that violence in childhood may leave a genetic mark as well. Researchers have found that children who are physically abused and bullied tend to have shorter telomeres — structures at the tips of chromosomes whose shrinkage has been linked to aging and disease."
Your kid learned to behave that way from you. You said it yourself about the environment you grew up in and that definitely affected you personality which in turn your kid picked up on.
Kids are 99% reflections of their caregivers.
I'm not saying that a spanking wasn't warranted but the situation would never have reached that point if they were raised differently.