What is wrong in this sentence is the pronoun their. As you can see, the pronoun <em>their </em>in this sentence refers to <em>the modern American family. </em>Since the word <em>family </em>is singular, the pronoun which modifies it also has to be singular. So, instead of using the pronoun <em>their, </em>it should be <em></em><u>its.</u>
Open accounts in Mexico. Due to the interest being higher there, they would earn more money off of putting their accounts in Mexico instead of the USA.