If this is a grafted tree then the 3 lower branches are sucker. If it is a cutting, then now. If the leave of the one look diferent than the main tree then they are probably suker. I would be inclined to remove them anyway

Steve

Yes, those three green branches are suckers from the rootstock.
Although I can't see the other side of the trunk, I will bet that the graft is in the union of the branches of that "Y" .

Yes, rootstock. You can even see (just) that they have trifoliate leaves.
Remove almost flush with the original trunk, or they will eventually take over!