Born in means you have no experience of life outside, all your connections are JWs and you are conditioned to accept JW doctrine and to follow the restrictions in their lives You have never had a proper childhood since your parent's love is conditional on you sharing their beliefs. They have had a miserable childhood and adolescence and devoted endless hours to meetings, assemblies, field service and bible study. They may have married someone with whom they have nothing in common because options are limited and the pressure to marry the first person you date is huge. If you decide to leave you are facing the loss of all your family and friends, they are poorly educated and have limited resources.
If you came in later in life you have a network of non JWs you can connect with. You have had a chance of a real childhood, education and a chance to enjoy your youth. You have experienced unconditional love and had a chance to make something of your life. If you wake up to the bullshit you have more resources and more options.
Just because the JW life is all you know it does not mean it is in anyway better to the experience of a life of freedom.