Hi Taku11, they used to think that your brain was fully developed at 18 months, now it is probably in your late teen years. That’s not to say that it wouldn’t grow with more memories after this point. Until your teens you are still making new connections in your brain and setting what is moral and ethically.
I’ve been looking into consciousness recently for Wonders, and it’s amazing that a foetus (a baby that is growing inside a female’s womb before it is born) has consciousness of its surroundings, and senses to experience the environment that it is in. There has been recent debate that they may feel pain earlier on in the pregnancy than people realised, and actually before the final cut off date for abortions to take place. It adds a whole new level to the argument of whether abortions are killing an innocent, conscious life, or whether it’s just a bunch of cells.