I have a question concerning restrictions on whether a man can ordain as a Buddhist monk. I recall watching the film 'Amongst White Clouds' recently where a monk spoke about being happy that he had a brother who could look after his parents following ordination as otherwise he would not be able to have become a monk. I'd never heard of this before. Although he was likely coming from a Chinese Mahayana perspective, I am wondering whether there are any rules in Thai Theraveda Buddhism that prevent a man from ordaining if they have parents who are likely to need financial and emotional assistance in old age and for whom he does not have siblings who could shoulder this responsibility.
I ask this question as over the past twelve months I have been seriously considering ordaining. However I have parents who are financially not well off and although not dependent upon me at the moment, I am conflicted between my concern for their future welfare and my wish to ordain which they have expressed their support for in the past.
Thank you for any insight you can provide