The will to kiss is inate (inborn) but the technique is from experience.

The Romans began the art of kissing. Yes I too believe it is an inborn trait. It is the physiacl act of saying I agree with you. Proverbs 24:26 says "Every man shall kiss his lips that gives a right answer."

I also belive it is inborn. Using the lips to show affection and/or goodwill is compleatly logical, since the lips are the most sensitive, exposed part of our body (using unexposed parts to express goodwill could land you in jail). We also see similar behavior in our closest reletives, the primates. They use their lips extensivly in social behavior, either to show affection or for grooming (picking vermin from someone else´s coat). Now some cultures don´t use the lips as an expression of social goodwill, but I belive that is a learned behavior, i.e. taboo.

There are more neural sensory endings in the lips than anywhere else on the body. Babies always place objects to their mouths due to the density and sensitivity of nerve endings in the lips. It only seems logical to carry that innate behavior into adulthood. If it is considered an inborn trait to eventually be able to walk on two feet, then kissing is inborn, otherwise, it is learned by environmental experiences and practices during infancy.

I heard somewhere that in the cave man days, when you transfered food to one another you might use the mouth-to-mouth technique, especially if that other person was sick or injured. This I suppose became a symbol of love and affection over the ages, and kissing just kinda came from that. Did you know that our species was the only (back then) to stop and care for hurt/sick members, and that it is our empathy that brought us to the top? Groovy.

Both. It is a practical habit that has become inborn in higher mammals. Kissing helps to transfer substances important to the human immune system from one human to another. This is why doctors recommend mothers kiss their babies often. Antibodies are given to the infant so that they can develop their own immunity. Ancient man no doubt (over many, many years) noticed that kissing was a good habit and (although probably beyond their understanding) resulted in healthier offspring. Frankly, those human genetic lines who kissed survived better than those who may not have kissed. Adaptation, variation and natural selection over millions of years. Kissing is also a form of psychological, mutual submission (translation: sign of affection, safety and tenderness). The mouth contains the teeth: the primay offensive and defensive weapon for mammals. Kissing involves putting this 'weapon' very close to another mammal's in a submissive way as if to say "I trust you and you can trust me." Much the same meaning as when a dog licks another dog's nose/face. Later, humans attached more romantic meanings to kissing. But early mammals and humans in particular had no reason to attach romantic meaning to kissing. It began as a very practical behavior.

Both.