A human being can smell a trillion kinds of smells. The way you look at different things also affect your smelling power, so studies have revealed that no two people can smell an odour the same unless they are identical twins.

What makes a smell good or bad?

It all depends on one’s genes that how one smells an odour. When you smell something, the odour’s molecules enter your nostrils and stick to sensory cells, olfactory receptors. A receptor is the cellular structure that responds to stimulation. A human nose has more than 400 such receptors. Different smells affect different receptors, which stimulate neurons around olfactory receptors. We smell differently because of different collection of neurons in us.

According to scientists, change in the genes of receptors affect understanding of a smell. Therefore two people smell an odour distinctly.

Researchers say the understanding of smell is present in genes, however it could be learnt as well. If a scent reminds you of a good memory, it is highly likely that you have penchant for it.

Why do men like some women’s smell?

Body odour is considered to be stench because bacteria break down proteins from sweat into acids. Researchers have revealed that men have penchant for scent of some women and detest others’. They took samples of smells from some women’s armpits and asked a group of men to smell them. The men were asked to categorise the smells according to the level of attractions, to dig out why smells of some women were more liked. They found out that the reason behind liking of one smell over other was the quantity of hormones in it. Presence of more estradiol and less progesterone in a body of woman was liked by men. The researchers said estradiol hormones also tell about capability of fertility in a woman.

In a separate research, it was found out that odour with spread-out molecules reek while the one with compact molecules smell sweetly.

Scent-manufacturing companies have highly-paid professionals who work for them to discern good fragrances from bad.