Why has no guy ever flirted with me or liked me?

I try really hard to be likeable. I put effort in my looks, personality and still no one has liked me. Even back in time when I didn't care about what people thought of me and just being myself still no one liked me. But my sister just gets men without even looking at them. What is wrong with me? I am 17 and no one has flirted with me in real life, complimented my looks or liked me.

Why has no guy ever flirted with me or liked me?
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