The answer is enzymes - 2 in particular - alcohol dehydrogenase and aldehyde dehydrogenase.

Alcohol dehydrogenase enables the body to convert alcohol into acetaldehyde, which is then converted into acetic acid by acetaldehyde dehydrogenase before being released from the body.

When men and women drink the same amount, women tend to experience more significant effects. The reason? Men have more of these enzymes in general, which makes them able to process and remove alcohol from the body faster.

Similarly, some ethnicities have lower levels of these enzymes. In particular, people of Asian or Native American descent will experience higher feelings of intoxication. People of Asian descent can have issues producing acetaldehyde dehydrogenase, instead generating a nonfunctional enzyme. People with this gene have intense flushing and unpleasant reactions to drinking alcohol - sometimes referred to as the Asian Flush or Asian Glow.

These cytokines are likely the culprit behind many cognitive effects of alcohol, such as memory impairment and mood changes.

Apart from these enzymes, your body composition also plays a role. Fat does not absorb alcohol, so people with more muscle mass can drink more without noticing the effects of alcohol as drastically.

As people age, they tend to have less muscle and more fat. So, older people may feel the effects of alcohol more strongly.

And while alcohol tolerance cannot be wholly attributed to these enzymes, they do play a role. The liver responds to repeated alcohol use by producing more of these enzymes, expecting more alcohol, leading to more rapid alcohol metabolism.

These cytokines are likely the culprit behind many cognitive effects of alcohol, such as memory impairment and mood changes.