Possible yes, but highly discouraged because entropy has to be generated securely.
As I explained, there is no reason for a person to choose seed words, except that he will try to remember them himself. If he plans to write them, it does not matter if you chose the words or someone else chose them. In the end, the difference will be a few seconds to recover the wallet, but it is a great damage to entropy (from 256/128 to less than 16 bit.)
If you are absolutely dead set on memorizing your seed phrase, at least make a paper back up as well.
If you were a person like me, you would need something to remind you of where you put the paper, as I forget a lot, so I do not advise anyone to rely on his memory.