Hispanics and Education: Lack of Motivation or Genes?

So I was on the internet, which is where I as most people spend many hours, and came across a few different articles on Hispanics and education. I think both are worth reading and present some interesting views.

The first article comes from the New York Times. The main finding can be seen in the first line:

"The children of Hispanic immigrants tend to be born healthy and start life on an intellectual par with other American children, but by the age of 2 they begin to lag in linguistic and cognitive skills, a new study by researchers at the University of California, Berkeley, shows." 

In the study it also says that low income whites and African Americans also fall behind on cognitive scores, but it is higher in Hispanics, especially those from Mexican backgrounds. One belief for the decline may be due to the education levels of Hispanic mothers, who usually have a lower education level than most other mothers of different ethnic backgrounds. One professor also remarks that you do not see children in lower income Latino households doing reading activities or saying their ABCs to their grandparents. The article then talks about how the Obama administration is investing 8 billion over eight years to states to start programs to promote learning skills in toddlers and pre-k students.

The other article comes from James Nava. In the article it talks about the high school drop outs in the Hispanic community. It argues that most in the community value education, and that the community needs stronger values like motivation to succeed in the community. At one point it also says that of the Hispanic students that were evaluated, 35% that dropped out were failing. The other 65% were actually doing well academically.

The question that needs to be asked is why? What causes this? I personally feel that the idea that it is a mental reason Hispanic students are failing seems illogical and a scapegoat excuse for explaining why one group of students are not doing well. Yes, the study does mention that it has to do with economic status, but the fact that "Mexicans"do worse on cognitive levels than others in low economic standings seems...almost ridiculous. If anything, I want to be in those houses the examiners went in. If the second article is correct, Hispanic families want their children to do well in school. Why would the grandparents not play word games with their children? I was raised in a middle class family, so maybe I don't understand. However, I feel like laying the blame in "cognitive" development skills seems too simple to be the actual explanation.