I'm 27 years old model and being under 8% body fat matters for me. I heard consumption of the right omega-3/6 ratio is important for this. I'm wondering whats the ideal ratio for my goal and why it is so important?
Several sources of information suggest that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 whereas in Western diets the ratio is 15/1-16.7/1
This is not undisputed though.
https://en.wikipedia.org/wiki/Omega-3_fatty_acid#Interconversion explains the importance. It's hard to summarize.
The book Living a Century or More by William Cortvriendt MD, which has a lot of scientific sources that I don't have the expertise to judge but seem reliable, says in the subchapter "Omega-3 PUFAs and inflammation" that
...COX can in fact stimulate or inhibit inflammation. When omega-3 PUFAs come into contact with COX, they will inhibit inflammation. However when COX comes into contact with omega-6 PUFAs then inflammation will be stimulated.
Note that inflammation is often an appropriate response by the body, but too much of it is harmful. This explains why the ratio is important: you don't want too little or too much. There may be other effects.
The ideal ratio is between 5:1 and 1:1 in favour of omega-6. The typical ratio is much higher in favour of omega-6. That's why food and supplements with omega-3 are popular.
EDIT: you're trying to have low body fat. Of course the ratio can be controlled in two ways: increase omega-3 or decrease omega-6. If you want to keep total fat low, you could consider limiting omega-6. But keep in mind that these are healthy, unsaturated fats. If that's an option, you should definitely cut trans fats instead, and maybe saturated fats.