a childs development is affected most by?

I am not an expert, there are some of those around. The following is based on my experinece as a teacher and parent:
1) Genetics
2) Early childhood nuturing (touching, stimulation, holding, talking to, etc)
3) Physical and nutritional environment in early childhood, including medical care.
4) Late toddler to Preschool. Nuturing, social contact (vice isolation), vicarious experiences in stories, play, and reading.
5) Preschool nuturing and pre-reading experiences.
6) After 7, the personality and equilibrium seems to be set, and the most important items in developement seems to be nutrition, stability, and social interactions.
Nuture means lack of emotional or physical trama, stable and supportive environment, with a close stable personal relationship with the caregiver. In my experience, it does not matter much who the caregiver is, as long as these are met.

I hope you get some more research based ideas.

I will add a little to the information provided by Bob Pursley. I am not an expert, either, but when I was in college (many years ago)I took a psychology course that dealt with child develoment. The question in those days was what was more important to child development; i.e., environment or heredity. The conclusion in those days was that each was equally important. I don't know if views have changed in the intervening years.

From experience I would second BobP's answer.
Like DrBob222 I had psychology and I think when I had it the argument was leaning more toward heredity, genetics, nature or whatever other term you want to use. I'm really not sure if there is a right answer to this question, or whether there is a provable one at any rate. It seems clear that nature and environment both affect development, but which has the greatest afffect probably varies by child. I don't know how else to answer the question...

how physical environment affects personality

The physical environment can have an impact on personality development in several ways. Here are a few ways in which the physical environment can affect personality:

1. Cultural Influence: The physical environment a person grows up in, including the country, region, and community, can have an influence on their beliefs, values, and behaviors. Different environments have different cultural norms and expectations, which can shape an individual's personality.

2. Social Interactions: The physical environment plays a role in shaping social interactions. For example, growing up in a crowded urban area with limited green spaces may lead to more crowded social interactions, whereas growing up in a rural area with open spaces may result in more relaxed and open social interactions. These different social environments can impact personality development.

3. Access to Resources: The physical environment can impact access to resources such as education, healthcare, and opportunities for personal growth. Lack of access to these resources can limit a person's potential and have an impact on their personality and overall development.

4. Environmental Stressors: The physical environment can include various stressors such as noise, pollution, or overcrowding, which can affect a person's emotional well-being and coping mechanisms. These stressors can influence personality traits such as anxiety, resilience, or adaptability.

5. Physical Safety and Security: Growing up in a physically safe and secure environment can contribute to a more stable and confident personality. On the other hand, growing up in an unsafe or unstable environment may lead to heightened anxiety, hypervigilance, or other personality traits as a means of self-protection.

It is important to note that while the physical environment can play a role in shaping personality, it is just one of many factors that influence personality development. Other factors such as genetics, family upbringing, and personal experiences also contribute to the formation of an individual's personality.