From WikiPilipinas: The Hip 'n Free Philippine Encyclopedia
'Anak' (Filipino for child) is a Tagalog song written by Filipino folk-singer Freddie Aguilar. It was a finalist for the inaugural 1977 Metropop Song Festival held in Manila. It has been translated to over a hundred local and international languages.
 Inspiration and Composition
Freddie Aguilar left family and school unfinished at the age of 18. His father, who had wanted him to be a lawyer, was disappointed. Freddie travelled to far-away places carrying with him, solely, his guitar. With no one to guide and discipline him, he got into gambling. Realizing and regretting his mistakes five years later, Freddie composed Anak, a remorse song expressing apology to his parents. He went back home and asked for forgiveness from his parents who welcomed him with open arms. After his father read the lyrics of Anak, the two became closer to each other. The homecoming proved timely as soon after, his father would pass away.
The song first starts out on how a boy's parents took very good care of him when he was a baby. It says that they stayed up late because he was crying for milk. Then, when the baby grows up, he doesn't respect his parents. They wonder what caused him or her to be like that.
Anak became a finalist in the first MetroPop Song Festival. It went on to become very popular in the Philippines and eventually abroad. The song generated a hundred cover versions, was released in 56 countries and in 26 different foreign languages, and it has sold 30 million copies. Because of this, it has given Freddie the distinction of being the only Asian artist to achieve worldwide fame. It was such a big hit that Billboard Magazine reported it as a No. 2 on its Top 100 Hits of the World in the ’80s!