I have a crush on this boy. He is older than me by a few years. He is my mum's uncle's son. Which makes it, my mum's cousin. So i have a crush on my mum's cousin. Is it wrong if i like him? Can i even get married with him? Is it haram?
Sherief, As-salamu alaykum,
Yes, you are allowed to marry a first cousin.
And yes, it does carry a slightly higher risk of birth defects in the children. Those who are telling you to ignore the science in this matter are foolish. The risk is very well known. Even animals avoiding breeding with close relations - their instinct tells them that it is bad for the species.
Among humans, we can see the effects of generations of inbreeding among European royalty. For centuries they married only other relatives, to preserve the "royal bloodline". The result? High rates of insanity, mental retardation and other birth defects.
Human populations of small islands are known to have higher rates of birth defects due to inbreeding - for example the famously high rates of deafness among the residents of Martha's Vineyard.
It's silly to say that we should ignore science because everything happens by the will of Allah. Would someone eat poisonous mushrooms and say, "Well, I won't get sick except by Allah's will". Or smoke cigarettes with the same excuse?
The Prophet Muhammad (sws) said, "Trust in Allah and tie your camel." In other words, have faith in Allah, but also take worldly precautions. Do your best to avoid needless problems and complications in life, then accept the results as Allah's Qadar.
Hostility or dismissiveness toward science is not an Islamic attitude. It's a product of lack of education. Science is nothing more than observation of nature, and drawing conclusions from that. Allah tells in many places in the Quran that natural phenomena are signs for those who reflect.
That is why historically, Muslims were pioneers in all areas of science, including mathematics, astronomy, cartography, and medicine. Unfortunately in the modern era we have fallen behind.
In any case, marrying outside the family is better. It brings new blood into the family, helps to unify the Ummah, and exposes people to new ideas and customs.