2 year old won’t stop biting

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My 2 year old nephew ( that sees me as his mom and lives with me and my family ) won’t stop biting me and only me I don’t know why but I’ve tried what seems like everything from biting back to , flicking in the teeth and being stern but nothing seem to work , any advice is greatly appreciated 😊 these are two thats are just from today and I have more but these are the most noticeable