How do I get dual citizenship as an American?

A child born to Mexican citizens is a Mexican citizen by birthright wherever born. You were born a Mexican citizen! All you need is proof of your parents' Mexican citizenship to get a Mexican passport. Your parents should have done this when you were born to protect your rights!

Yes, there are certain restrictions on foreigners owning property in Mexico. Your Mexican citizenship is important.

You can ONLY enter/exit US on your US passport. Enter/exit Mexico ONLY on your Mexican passport. Your obligations to the US include filing your annual income tax returns & paying US income taxes on all income from all sources worldwide, regardless where you reside. Plus you are subject to reporting requirements of all foreign bank & financial accounts, and foreign assets. If you, for example, rent out your property in Mexico, that income is US-taxable. However, as a dual-national, if you decide to remain in Mexico permanently, you have Mexican citizenship and can renounce US citizenship if you decide to.

Your other obligation to US, if you are male, is to register for Selective Service within 30 days of turning 18. Otherwise, you can come & go, or stay out of US for the rest of your life - as long as you pay your taxes. That's all the US govt cares about. No fuss over your dual-nationality.

Since you have been a Mexican since the day you were born, there's nothing you can do to become a Mexican. Neither is there anything a dog can do to become a dog.

if your parents are citizens in mexico then you are a citizen too

Visit the embassy, and ask for assistance.

You are already a dual citizen of USA and Mexico. You have been since you were born.

You can apply for a Mexican passport at the nearest Mexican embassy or consulate if you like.

Your already Mexican so you can't become Mexican.