Why do I tan so easily?

I protect my skin with spf and all that sunblock crap. But every time I leave the house in 80+ degree weather, I come back 2-3 shades darker and I get the worst tan lines. This made me so mad. I decided to only leave the house at night.
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+1 y
i thought the melanin prevents you from getting darker that quick.
Why do I tan so easily?
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