No more than it is essential to be 100% sure that a painting does not depict a real-life person.

A painting is usually immediately recognizable as a work of art / fiction. Do you want to appear as a team member on an escort service site which uses automatically generated placeholder images to protect their employees? Do you want your face on a billboard ad for Viagra?

There is a huge difference between "hey, that painting looks like you" and "hey, that is a photograph of you".

That almost certainly isn't needed for a project like this, but I wonder if it would be needed to try to make money off this. It might be like the whole "The events depicted in this movie are fictitious..." warning you see at the end of almost every movie regardless of it is some realistic and plausible story or if it something like Avatar.

Why? Is it illegal to look like someone else? I look like my sister and my dad.