'True' and 'correct' are not the same thing.
Is it true?
A mother's love does indeed usually come naturally, though not always.
Is it correct?
As it stands, no. At the very least you should change 'came' to 'comes'.
But it COULD be correct IF it followed a sentence that said something like "A child's love for its mother comes naturally."
In that case, the 'as naturally' at the end of the second sentence would match the 'naturally' in the first sentence.
"A child's love for its mother comes naturally. A mother's love is intrinsic, that comes as naturally" [as a child's love for its mother]
We don't need to SAY "as a child's love for its mother", but we would know, from reading the sentence before it, that this is what is meant.