Its possible to memorize your recovery phrase and It is 100% risky if you only rely on it so it is advisable not rely on your memory as your only method to store your recovery phrase and I wouldn't encourage you to write it down in a piece of paper since your house isn't secure. Important documents store and kept in the house couldn't be stolen,eaten by rodents or possibly got burn by accidental fire or got swept by flood so the best method I can recommend for you to store your recovery phrase is your Google Mail  or you can snap it and backup it in you google photos.