Approximately 80 years ago, quadruplets Nora, Iris, Myra, and Hester Genain were born. All four sisters were diagnosed with schizophrenia. This scenario highlights some key points in the battle of nature vs. nurture. Even though they were identical sisters, they varied in weight. Two of them, Iris and Hester, weighed significantly less than the other two, Nora and Myra. Three of the four sisters were hospitalized due to their disorders, leaving Nora to be the only "strong" sister. Whether it was because Iris and Hester severely weighed less or not, their mother favored Nora and Myra. She would even go to the extent of punishing Iris and Hester for inappropriate behavior. Myra was her favorite though, to the point where she said that she thought Myra was psychologically healthier and smarter than the other three. Myra went on to get married and held a job position for many years. I see different ways of nurture every day. Had the Genain family only had twins or triplets, the way they raised them would have been very different. Had Myra not been born, the parents would have treated each of the other three daughters a lot better, and not have caused as muc stress on them later in life. My brother and I are, even though a few years apart, very similar. We are about the same height, have similar personalities, and like many of the same things, but we act differently because of how our parents raised us with the knowledge they had. He is older than me, so my parents had a few years to raise him before I was born. They learned things while raising him that they did differently with me. Humans develop differently based on their nature and nurture, and no person can be raised the exact same way.
I would tend to agree with you, specifically with the part about your brother and you. Me and my sister are the same way. Myself, being 3 years older and being raised an only child for 3 years I am in some ways less independent than she is because my parents were able to focus 100% of their attention on me for three years.