The thought has been going around for at least 80 years that some part or all of the poinsettia plant is poisonous.
But research has shown that actually no part of the poinsettia plant is poisonous so you can safely have the poinsettia plant around young children and pets and it will not do any harm to your pets or children other than maybe give them an upset stomach, vomiting etc.
Also the leaves may present a choking hazard to young children if they try to eat the leaves of the poinsettia plant but other than that the poinsettia plant is not toxic to animals or people even though it should not be eaten.