I think we are all born with this,its just that some people are really gifted at it.Its kind of like drawing..we can all draw but there are different levels of drawing..for example some of us draw like a young child and then there are the really gifted artists who can draw or paint brilliantly.
I think mediumship is a bit like that.
We're all psychic as well I think,but we put it down to imagination and as real life gets in the way we forget about the messages we recieve.
I think intuition grows stronger the more its paid attention to,the more you trust your "gut instincts" the more powerful they become..but you have to really pay attention to those little feelings you get for them to grow stronger.
For me what helped was just an openness to all things spiritual,reading about it,watching it on tv and mixing with like minded people seemed to enhance what I was receiving.
You can go to psychic workshops etc ,although I don't think these are for me.I've actually learned alot from some good online spiritual groups I've been in.
But yes I think we're born with itx