Matthew was running with the in crowd in Longview TX as a kid. His mom and dads were country club members and she was involved with the museum/art crowd in Longview, TX. From what I gather the probably had a ranch on the border. Wouldn't be surprised to learn they used slave Mexican labor. His dad had quite the large gut on him judging from the picture. I'm not sure I believe the whole story about him having a heart attack while busting a nut in his wife Kay.
https://www.newspapers.com/image/215295077/?terms=Matthew%20Mcconaughey&match=1
https://www.newspapers.com/image/208357719/?terms=jim%20Mcconaughey&match=1
https://www.newspapers.com/image/191311890/?terms=jim%20Mcconaughey&match=1