Say one has reasons to suspect that their mother is Jewish and thus, they too would be Jewish but they lack hard proof, should they celebrate Jewish holidays just in case?
Are they halachically permitted to celebrate Jewish holidays or are they forbidden? Can they partially observe them?
Do they gain any spiritual reward from (even partially) doing them (e.g. more specifically its almost Yom Kippur now, so this is the specific one that I'm talking about in this context)?