Even most unbelievers take care of their own families/relatives in distress. What kind of testimony would we, Christ's followers, be giving to the world if we don't provide for our own families (who cannot provide for themselves)? It would be denying the Christian faith (bringing disgrace to the name of Christ) and we would be worse off than the unsaved. We must take this responsibility seriously. The command to honor your parents (Exodus 20:12) does not have time limit/age limit. Jesus honored Mary, His mother, by making sure she would be taken care of by John after His death.
"The only thing that counts is faith expressing itself through love." (Galatians 5:6b) Authentic faith will be expressed through genuine love for God and for others (including our own relatives). Love in action is caring, assisting, supporting, giving, providing, meeting their needs. "Faith by itself, if it is not accompanied by action, is dead." (James 2:17)
"Many wait to live a life of self-denial on the mission field instead of living in such a way in their own home." (Greg Gordon)