We're only going to say this once.

shintô practices are culture. Culture is NOT genetically inherited. Culture is learned.

Now granted, if you're not raised in a culture, you've got a lot to catch up on. It may take you many years to develop the implicit knowledge that one acquires growing up embedded in a culture.

On the other hand, you can choose which items of implicit knowledge to acquire; something a person raised in a culture doesn't always have the option of doing.

In fact, even if you're Japanese, if you were raised in another country, most likely you have the implicit knowledge of that county's culture; not that of Japan's Japanese culture.

So just forget about genetics.

If you want to learn Japanese culture and practice shintô, 頑張って [ がんばって / ganbatte] — Go for it!