Should I invite my female cousin to go to the lake with me (I'm a guy and live in the U.S.)?

“ We are basically best friends and spend time together at a lot of family gatherings.” is what you have mentioned.

It all depends on how you see her, and your relationship with her.

1. Whether you see her as your cousin(sister) or a friend???

If brother-sister bond is strong. And you see her as your sister, go ahead.

2. If it is mere friendship and the feeling of brother-sister is nonexistent,

don’t go.

You are a 23 year old and know what I mean

[Incest has grave consequences]. If there is even 1% of lust don’t go.

3. [since this question is asked, it is almost certain that you are confused].

i) If you doubt/confused on how you see her don’t go.

She is not just another girl, it is your own blood. DON’T GO

ii) If your confusion is how others perceive it, leave it to your guts.

To know more about INCEST and its Ill Effects

• The Problem With Incest
• Effects of incest. Reporting incest. Resources for victims -NOVA

[The question lacks clarity; is it about what people might(society) say Or is it the feeling your for her or something else. You have left the part unanswered hence people assume according to their free will]