Whenever I raise the issue of "kids are so bratty" my mom spouts off the "If the parents are good, the kids are good" theory. And then I start giving her examples: a lovely woman she worked with who had a complete [censored] of a daughter; son #3 of a relative who ended up dealing drugs and has cut off almost all relationships with extended family; daughter of another friend whose father struggled to put her through school, who promptly gave up her profession as soon as she got married; I could go on forever.

Good parenting is essential, however what people never realize before having kids is that they don't always turn out like the parents. Heredity is a strange thing: we inherit characteristics from our aunts, uncles, grandparents, etc. as well as our parents. My own brother is much more like my uncle than he is like our parents. So if you have relatives with questionable traits (who doesn't?) these could always turn up in your kids. Another thing is that personality is not constant: a lot of people are shy when they are young but talkative as adults, and a traumatic event like losing a job or a spouse can really change someone's outlook on life, making them act completely different. So a child's personality is not necessarily indicative of what they'll be like as an adult.