Yes, IQ is largely dictated by genetics. While environment has impacts on a person's overall IQ, there are many genetic diseases that impede brain growth or make it difficult for people to learn things. Some of these affects can be coached out of a person, but things like Downs Syndrome, autism and ADD all are genetic issues that make IQ drop.
I believe that genetics can help determine IQ, but with everything environment can play a role as well. Researchers have found that IQ is connected to genetics, which is interesting, but I think we need to remember that the IQ test is a man made test and it is not free of flaws itself.
I think both factors are components in determining IQ. There is definitely a hereditary component, but environment plays a huge role as well. There are instances where individuals with high IQ's are born to parents who are average. There are also instances when parents with higer IQ's have offpsring with lower ones. Growing up in an environment that fosters learning and is challenging has to affect intelligence. I don't know which is more important. In any event, having a high IQ doesn't matter if one doesn't use it.
I don't think you are born smarter than anyone else. Of course there are some exceptions with people who aren't average, or who might be disabled etc... And there are some people who are more capable to do certain things such as sports, and those sports might train certain parts of your brain so they might have some advantages but that does not mean they are born with a higher IQ. Some people are born in more advantaged houses who might provide more education or make it easier for the kid to concentrate on work, but that does not mean someone who is born in a household where they could not afford education or educational toys growing up, or don't talk about the current events at the dinner table where born with a lower IQ.. Some people might be born more capable to do certain things but mostly certain people arent born smarter.
To think that a person can just be born smart is a bit presumptuous. Some people are born with certain gifts. I'm not sure that these gifts are due to genetics. I think many things may impact the development of a child and we do not fully understand them yet. Even the most fertile mind may be stunted through environment or an unsupportive social structure. You may be born smart, but turned dumb by those around you. You can also be born average but afforded teachers and tutors that account for higher scores. I always say that I'm no smarter than any man, I was just exposed to more things than some people.
Genes can determine various things about the human, however I don't believe they determine whether or not you are smart or dumb. That is something that the indidvudal will decide throughout their life with their actions. Even people born with deficiencies have the potential, thought harder than most people, to become smarter.