how to grow your abs

Abs are made in the gym and revealed in the kitchen and controlled by practising ​uddiyana bandha (or stomach vacuums)

Abs are revealed by what you're consuming (or not consuming) in the kitchen. And like any other muscle group, their growth is thanks to the gym. Although there may be some people blessed with genetics that allow them to have more developed abs than others, it doesn't mean it isn't attainable by anyone else. Some people are born with more natural separation than others and might not need to directly work their abs to have a visible six-pack. And others who have thinner abdominal muscle bellies might not have that separation even when they're super lean.
Abs are made in the kitchen.... This expression comes from two things: You can do a million reps of various ab exercises, but if you have too much fat covering them you won't see a six pack. Some people who are very lean have abdominal definition even if they don't train them (or train at all). So it's pretty easy to jump to the conclusion that the secret to having abs is getting lean, which most people believe to be solely diet thing. 
But it isn't completely correct. If you aren't genetically 'lucky' so-to-speak in the abadabas department. You will just have to work for it. Which is great too because you can choose which abs to focus on for growth to get the midsection of your dreams.
Here are a few of my favourite weighted ab exercises stimulating abdominal muscle growth.