These verses are not claiming we are brother's and sister's with Jesus Christ. The verse 10 explains why it says "call THEM brethren". "bringing many sons to glory"
Are you a product of your mother and father or of God? Do you cry out Abba? Do you pray to your Father in heaven or someone elses Father?Romans 8:1 Therefore there is now no condemnation for those who are in Christ Jesus. 2 For the law of the Spirit of life in Christ Jesus has set you free from the law of sin and of death. 3 For what the Law could not do, weak as it was through the flesh, God did: sending His own Son in the likeness of sinful flesh and as an offering for sin, He condemned sin in the flesh, 4 so that the requirement of the Law might be fulfilled in us, who do not walk according to the flesh but according to the Spirit. 5 For those who are according to the flesh set their minds on the things of the flesh, but those who are according to the Spirit, the things of the Spirit. 6 For the mind set on the flesh is death, but the mind set on the Spirit is life and peace, 7 because the mind set on the flesh is hostile toward God; for it does not subject itself to the law of God, for it is not even able to do so, 8 and those who are in the flesh cannot please God. 9 However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. 10 If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness. 11 But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who dwells in you. 12 So then, brethren, we are under obligation, not to the flesh, to live according to the flesh - 13 for if you are living according to the flesh, you must die; but if by the Spirit you are putting to death the deeds of the body, you will live. 14 For all who are being led by the Spirit of God, these are sons of God. 15
For you have not received a spirit of slavery leading to fear again, but you have received a spirit of adoption as sons by which we cry out, "Abba! Father!" 16 The Spirit Himself testifies with our spirit that we are children of God, 17 and if children, heirs also, heirs of God and fellow heirs with Christ, if indeed we suffer with Him so that we may also be glorified with Him. 18 For I consider that the sufferings of this present time are not worthy to be compared with the glory that is to be revealed to us. 19 For the anxious longing of the creation waits eagerly for the revealing of the sons of God. 20 For the creation was subjected to futility, not willingly, but because of Him who subjected it, in hope 21 that the creation itself also will be set free from its slavery to corruption into the freedom of the glory of the children of God. 22 For we know that the whole creation groans and suffers the pains of childbirth together until now. 23 And not only this, but also we ourselves, having the first fruits of the Spirit, even we ourselves groan within ourselves, waiting eagerly for our adoption as sons, the redemption of our body. 24 For in hope we have been saved, but hope that is seen is not hope; for who hopes for what he already sees? 25 But if we hope for what we do not see, with perseverance we wait eagerly for it.
Galatians 4:1 Now I say, as long as the heir is a child, he does not differ at all from a slave although he is owner of everything, 2 but he is under guardians and managers until the date set by the father. 3 So also we, while we were children, were held in bondage under the elemental things of the world. 4 But when the fullness of the time came, God sent forth His Son, born of a woman, born under the Law, 5 so that He might redeem those who were under the Law, that we might receive the adoption as sons.
6 Because you are sons, God has sent forth the Spirit of His Son into our hearts, crying, "Abba! Father!" 7 Therefore you are no longer a slave, but a son; and if a son, then an heir through God. 8 However at that time, when you did not know God, you were slaves to those which by nature are no gods. 9 But now that you have come to know God, or rather to be known by God, how is it that you turn back again to the weak and worthless elemental things, to which you desire to be enslaved all over again? 10 You observe days and months and seasons and years. 11 I fear for you, that perhaps I have labored over you in vain. 12 I beg of you, brethren, become as I am, for I also have become as you are. You have done me no wrong; 13 but you know that it was because of a bodily illness that I preached the gospel to you the first time; 14 and that which was a trial to you in my bodily condition you did not despise or loathe, but you received me as an angel of God, as Christ Jesus Himself. 15 Where then is that sense of blessing you had? For I bear you witness that, if possible, you would have plucked out your eyes and given them to me. 16 So have I become your enemy by telling you the truth? 17 They eagerly seek you, not commendably, but they wish to shut you out so that you will seek them. 18 But it is good always to be eagerly sought in a commendable manner, and not only when I am present with you. 19 My children, with whom I am again in labor until Christ is formed in you- 20 but I could wish to be present with you now and to change my tone, for I am perplexed about you.