He wants to get married to a woman whom his parents rejected because of a physical defect in her
Question

                Are physical defects such as a curvature of the spine or in the body regarded as legitimate reasons for parents to refuse to let me marry the one whom I have chosen? Please note that she is religiously committed, of good character and of sound mind. May Allah reward you with good.
Praise be to Allah.
      Firstly: 

    A man should choose for himself a woman who is religiously 
    committed and of good character, because the Prophet (blessings and peace of 
    Allah be upon him) said: “Women may be married for four things: their 
    wealth, their lineage, their beauty and their religious commitment. Choose 
    the one who is religiously-committed, may your hands be rubbed with dust 
    (i.e., may you prosper).” Narrated by al-Bukhaari, 4802; Muslim, 1466. 

    He may marry a woman who is sick or has a disability or has a 
    physical defect, because he has the right to choose and it is up to him. 

    Secondly: 

    A man should ask his parents’ permission to get married and 
    consult them concerning the one to whom he wants to propose, and he should 
    try to please them because of the great rights that they have over him. 

    If he wants to marry a particular woman and his parents tell 
    him not to marry her, then he should obey them so long as he does not fear 
    that he will fall into haraam if he does not marry this particular woman. 
    Ibn Salaah, al-Nawawi and Ibn Hilaal stated – as mentioned by al-‘Allaamah 
    Muhammad Mawlood al-Mauritani in Nuzum al-Baroor – that it is 
    obligatory to obey one’s father if he forbids his son to marry a particular 
    woman. 

    But if he fears falling into haraam with this woman, then 
    warding off evil is to be given precedence over obeying his parents.  

    If you are keen to marry this woman, then you should convince 
    your parents of the reasons why you have chosen her. Then if they agree, 
    praise be to Allah, but if they insist on refusing, then it is better for 
    you to obey them. 

    You should not let that upset you, for Allah has put a great 
    deal of good and blessing in obedience to them (parents). It is no secret 
    that the parents have great rights and virtues which call one to show 
    gratitude towards them and to honour them and treat them kindly, and to 
    sacrifice a great deal of pleasures for their sake. 

    May Allah help us and you to do righteous deeds. 

    And Allah knows best.