Your Dad was right. Locks are really there to deter casual attempts to get into things. By themselves they aren't going to stop someone who is determined to get into you house or stuff. Layering your security (using steel doors and frames, deadbolts, alarms, noisy dogs, security screens, cameras, etc...) increases your chances of keeping people out. The longer it takes / harder it looks to get in, the higher the odds that a dishonest person will just give up or outright skip your place for an easier target.When I was a kid, my dad had a business next door to our small, rural home. Although he always said, "A lock will only keep an honest man out," we did lock our doors at night.