Sixty percent of the human brain is made up of fat,it doesn't make it the fattiest organ in the human body, but these fatty acids are crucial for your brain performance. Make sure you're fueling it appropriately with healthy brain boosting nutrients.
Again, your brain isn't fully formed untill age 25. Brain development begins from the back of the brain and works its way to the front. Therefore, your frontal loves, which control planning and reasoning are the last to straighten and structure connections.
https://www.hopkinsmedicine.org/health/conditions-and-diseases/anatomy-of-the-brain
Your brain capacity is considered virtually unlimited. Research suggest that the human brain consist of about 86 billion neurons each neurons, which could add up to 1 quadrillion (1,000tillion) connections. Overtime, these neurons can combine, increasing storage capacity. However, in Alzheimer's disease, for example, many neurons can become damaged and stop working particularly affecting the me memory.