Yes they do unless there is a birth defect.
Not true. Each person carries the genetic variability of their entire complement of ancestors, thus if the parents have below average IQs and it is caused genetically, they can still pass on genes that will produce normal intellectual capability or even better than normal intellectual capability. However, a significant component to IQ also includes both pre and post-natal environmental factors. If the mother is malnourished, ill or abusing drugs/alcohol while pregnant, it can affect fetal development. If a child is malnourished or abused, it can affect intellectual development and even receiving a substandard or no education can affect intellectual development.
The problem here is equating high IQ with smarts. George W Bush had an IQ of 120.
That is what they taught me growing up in the North.
Down South they claim it was about state's Rights.
Certainly one right the Southern states did not want to lose was slavery but:
1) Lincoln was not going to free the slaves. He did not want a Civil War
2) Lincoln only freed the slaves after the South seceded. This was to stop England from getting involved under the guise of the Civil War being about a moral issue of slavery.
3) The Northern Industrial Giants abused the South and essential made them captive to buy from their businesses by the use of extreme tariffs on European products while Europe was the big customer of the South's Agriculture products. Ships went over full and came back empty.
4) The vast majority of the populace of the South had no dealings with slavery. They had no dog in the fight of the plantation owners. The others whites were often doing the same work as the slaves or they had a small business. Because History is being rewritten now, I will not try to quote you a number. It is safe to say that the average Joe in the South could not afford a slave and also did not have a need.
5) The largest fear of the non-slave owning part of the population would be that 3 million freed slaves would suddenly be released into their states and create chaos. It would also destroy the state's revenue sources and just like today's society we depend on the wealthy part of society to buy in excess to create jobs for the lower classes.
Abraham Lincoln was not that noble. If the South did not Secede then slavery would have continued past Lincoln until enough new states were added to force their hand. Some slaves lived as well as some white men in the South. It was just about survival for a white sharecropper. 3000 slave owners in the South were black themselves.
So there is some truth in both sides. Much of what we learned in schools were fables.
No, they didn't. We've been through this before. Read the secession declarations. Sure, slavery is part of it, as an example of a federal transgression among other transgressions. The declaration read much like, were modeled on the Declaration of Independence. The main cause was to protect state's rights, then, as a means of protecting the rights of the people against a centralizing and intrusive government.