A family adopted him because his family were bad people, and they gave him their name; what are the consequences of that?
Question

                I am fifteen years old. I was adopted by an Afghan family when I was six months old, because my parents were bad people and they were not raising me properly. My name has been changed, but I was not breastfed by my adoptive mother. Does that mean that she is not a mahram to me and that she should not appear before me? What are the rulings in my situation?
Praise be to Allah.
    Firstly: 

    At the beginning of Islam, adoption was 
    permissible and the adopted child would be named after the one who adopted 
    him. Then Allah, may He be exalted, forbade it and ordained that everyone 
    should be named after his (biological) father. 

    Allah, may He be exalted, said 
    (interpretation of the meaning):

    “nor 
    has He made your adopted sons your real sons. That is but your saying with 
    your mouths. But Allah says the truth, and He guides to the (Right) Way.

    Call them (adopted sons) by (the 
    names of) their fathers, that is more just with Allah. But if you know not 
    their fathers (names, call them) your brothers in faith and Mawaleekum (your 
    freed slaves). And there is no sin on you if you make a mistake therein, 
    except in regard to what your hearts deliberately intend. And Allah is Ever 
    Oft-Forgiving, Most Merciful”

    [al-Ahzaab 33:4-5]. 

    It is not known that there was ever any 
    difference of opinion among the scholars concerning this ruling. 

    It says in al-Mawsoo‘ah al-Fiqhiyyah 
    (10/121, 122): 

    Islam forbids adoption and deems all its 
    consequences to be invalid. That is because Allah, may He be exalted, says 
    (interpretation of the meaning):

    “nor has He made your adopted 
    sons your real sons” [al-Ahzaab 33:4] 
    and “Call them 
    (adopted sons) by (the names of) their fathers” [al-Ahzaab 33:5]. 

    Adoption was known among the Arabs during 
    the Jaahiliyyah and after Islam came. During the Jaahiliyyah, if a man 
    admired another’s man strength and looks, he would take him as a son and 
    give him his name, and give him the share of one of his own sons in terms of 
    inheritance, and he would be attributed to him as “So and so [the adopted 
    son] the son of So and so [the adoptive father].” The Messenger (blessings 
    and peace of Allah be upon him) adopted Zayd ibn Haarithah before Allah 
    honoured him with the message, and he used to be called “Zayd ibn Muhammad”. 
    This is how it remained until the words of Allah, may He be exalted, were 
    revealed: “nor has He 
    made your adopted sons your real sons... And Allah is Ever Oft-Forgiving, 
    Most Merciful” [al-Ahzaab 33:4-5]. 
    Thus Allah abolished the system of adoption and instructed those who had 
    adopted someone not to attribute him to himself; rather he was to be 
    attributed to his (biological) father, if he had a father who was known. If 
    his father was unknown, he was to be called “mawla” or a “brother in faith”. 
    Thus the people were forbidden to change realities, and the rights of 
    inheritance were prevented from being lost or reduced. End quote. 

    Based on that, that family must hasten to 
    set straight that which they had done wrong. They have to cancel your 
    attribution to them in official papers and documents, and they must set 
    things straight in accordance with sharee‘ah. That is to be done by 
    testifying to your real lineage and confirming that with documentation to 
    that effect. The fact that the parents are bad people is not an excuse to 
    deny one’s blood relationship to them. 

    From this you will know the answer to the 
    basic issue of the question, which is that if a family adopts a male or a 
    female, there is no blood relationship between them as a result of that 
    adoption. Based on that, they are non-mahrams and it is not permissible to 
    interact with them as families interact, according to the rulings. The woman 
    who adopted you is a non-mahram to you, and it is not permissible for you to 
    see her, let alone touch her or kiss her when you are not a mahram to her or 
    to her daughters. 

    The Prophet (blessings and peace of Allah be 
    upon him) married the ex-wife of his adopted son Zayd – namely Zaynab bint 
    Jahsh (may Allah be pleased with her) after Zayd divorced her. This was a 
    practical application on the part of the Messenger (blessings and peace of 
    Allah be upon him) of the ruling that annulled the effects of adoption. 

    Yes, if that woman who adopted a child 
    breastfed the adopted child five times before the age of two years, then he 
    would become a son to her through breastfeeding, and her husband would 
    become a father to him through breastfeeding, and their children would all 
    become brothers and sisters to him through breastfeeding. But as that did 
    not happen – according to what you say – then that woman is a non-mahram to 
    you, and she must observe hijab before you and interact with you as a 
    non-mahram woman would. 

    You should honour that family and take an 
    interest in their affairs and keep in touch with them, because of the favour 
    they have done to you. 

    For more information, please see the answers 
    to questions no. 4696, 6102 and 
    95216.

    And Allah knows best.