The Science of Friendships

Having made some new friends last weekend, just out of curiosity I did a little research on whether something similar to pheromones effected human friendships, of the same sex. I was quickly enveloped in a morass of scientific arguments (even that humans could sense pheromones at all) that also tossed in genotypes and phenotypes.  Well that certainly wasn't what I wanted to find out.

But never one to give up, I'm now expanding my query to not only friendships, but possibly our relationships to our pets and animals.  We definitely feel more of an affinity for some rather than others.  What causes that?  Do pheromones (or something)  play a part in any of it?  Maybe it would be more accurately called interomones?

Pheromone A chemical produced by a given species that affects the behavior or physiology of the same species. The first example was bombykol produced by the female silkworm to attract males (A. Butenandt, P. Karlson and M. Luscher, 1959. Pheromones: a new term for a class of biologically active substances. Nature 183 (4653): 55–56.
Allelochemical Broad class of chemicals produced by a given species that can have beneficial or harmful effects on the same or other species. Many examples in plants, insects and vertebrates. Ex., plant chemicals that prevent the growth of other plants in the surrounding soil. http://en.wikipedia.org/wiki/Allelochemical
Allomone Chemical produced and released by one species that affects the behavior or physiology of another species to the benefit of the originator but not the receiver. Plant chemicals released to defend against insect species. Grasswitz, T.R. and G.R. Jones (2002). "Chemical Ecology". Encyclopedia of Life Sciences. John Wiley & Sons, Ltd. doi:10.1038/npg.els.0001716
Kairomone Chemical produced and released by one species that benefits another species, but not benefiting and often harming the emitter. Insect predators use them to find prey. Ponderosa Pine produces a terpene called myrcene when the Western pine beetle damages the tree which lures more beetles to the tree. Wyatt, T.D. (2003). Pheromones and Animal Behaviour: Communication by Smell and Taste, First Edition (Cambridge, UK: Cambridge University Press).
Synomone Chemical produced and released by one species that benefits both the emitter and receiver. Plant odors that attract bees. Plants attracts bees to feed and then the bees take the pollen to fertilize other plants/flowers. http://en.wikipedia.org/wiki/Allomone
Interomone Chemical produced and released by one species that has an effect on another species behavior or physiology. Interomone is a broad term that applies to chemicals that benefit or do not benefit the emitting, receiving or a third party species. Pig sexual/social pheromone that causes barking/jumping/begging dogs to stop. New term
http://www.depts.ttu.edu/animalwelfare/Research/Pheromones/

Just wondering. I'm just not sure that it all has to be related specifically to sex.  However, I scientist I am not.