Thank's for the response...it's just I'm new to this culture, I'bve always had a keen interest in magick and the occult, it's just that society deems it un becoming, but I just recently found out what it is and how it can be used for the good mankind... Uhm... If that's the right way to put it...thank you!
Psychic capability is not inherently hereditary as it involve subtle (non-physical) senses rather than physical dna. This being said, there are certain cases where a bloodline has been more naturally in tune with their abilities or a family that actively incorporates it into their lives. Anyone can develop the ability and don't be discouraged if you don't get something right away as it takes time to develop skill. Recognizing certain things will also aid. Having a personal item or piece of their dna typically helps make a better connection, though it would be best to understand how to communicate wtih spirits and the best way for anyone there is to trust their instincts or gut feelings as spirits are not always verbal.
Not everyone is able to project well, though if you can, all the more power to you. As for the dna, you don't need it, though it does help. The simplest way to talk to a spirit is to turn your awareness to them, talk, and listen , not just with your ears, but with your intuition. Your gut feeling will most of the time tell you what they are trying to say.
No, you dont have to be born from a witches or shamans bloodline. Artifacts do help connect you to whom you wish to communitcate with. But before you summon any spirits to the physical plane, purify your area so that negative energy and entities dont pass through the astral plane and make things hard on you and your family. If spirit summonings go wrong, hauntings happen and you might have to do a strong banishment spell to banish the negative energies. Oijia boards are good for communications, but like I said, purify it before you use it and after.
While Melody's advice is good, I'd like to point out that spirits aren't summoned to the physical plane. There is a belief that they can influence the physical and calling up a spirit can make their presence more known, but they will not physically materialize.