How to get past being tagged as overly curious and unfocussed? I am in a reputed PhD Programme in Computer Science. In the prior part of my PhD I was focussed on applicative research but during the course of time I developed a keen interest in the theoretical reasoning behind algorithms and methods. I would have liked to prove the correctness of my work theoretically along with the experimental results. Since I didn't have a very strong fundamental background in mathematics, I developed a habit of asking "why" behind every assumption made in any topic. For example: I had a 15 minute long discussion with my lab mate on why the sample event space for calculating probability consists of a null set and what does it mean.

Our lab has weekly presentations by various students of my lab about their research topics or something else, focussed towards people who don't know anything. My obsession to understand the fundamentals have probably led me to be able to ask questions even upon topics not remotely concerned with my field of study. And I do ask questions (I don't know about the quality of questions since I am mostly not very well versed with the topics being presented). I somehow also have a habit of being able to relate things from various fields of study, so after or during the presentations I am usually able to find the connection between my and the other person's field. 

Due to this, my advisor (occasionally and in a positive manner) and other people have started tagging me as overly curious. A few students make fun of me behind me, saying why the hell I can dive into discussions with people working in String theory when I don't have to work upon it. 

Though I am producing results (coding, studying and teaching the same to my co-authors) and mostly the one who brings new ideas to the table, I am mostly taunted as being unfocussed by my lab mates when I just try to discuss about some random idea during coffee or lunch break or try to know about a new project initiated in other labs. Earlier I chose to address their concerns and accepted that maybe I have a problem, but with time people even question my focus when I just express my wish to attend an advanced Algebra lecture (an hour a week). This hasn't killed my curiosity but has led me to question my abilities and is affecting my self-confidence. I am an excellent team player, but due to continuous taunting I prefer working and hanging out alone (against my nature) since I think I am negatively impacting others' work.

My questions are:


Does it make sense to attend these weekly presentations whose main aim in my view was to develop a habit of asking questions? 
Is wanting to know about other people's work, even from other domains, considered as lack of focus?
Is there something called "overly curious" ?
Answers to your questions are dependent on the culture you are in, and how you, personally, want to cope with the norms and values of that culture.

For example, in some cultures, it is possible to be labeled "overly ambitious" if one voices the ambition to be the "best X in the world", or even "the top X in our country".  This doesn't apply to the US, where open ambition is rarely stigmatized.

Also, be aware that your class mates and lab mates may be taunting you and make fun of you as a way to cope with their own discomforts and insecurities. Such reactions are hardly useful or informative to you as you develop your skills and capabilities in a way that suits your disposition and inclinations.

Here are my answers to your questions:


  
  Does it make sense to attend these weekly presentations whose main aim in my view was to develop a habit of asking questions.
  


Yes, this is perfectly fine if it doesn't take away time or energy from your other work and doesn't delay progress in your PhD program. As my (well-regarded) adviser says: "Intellectual curiosity is very valuable in academic life. It is not widely distributed and it is hard to develop if you don't already have it".


  
  Does wanting to know about other people's work; even from other domains considered as lack of focus.
  


No, not in and of itself.  This is the way of the "polymath".  You might just start telling people: "I'm a polymath, or aspiring polymath.  This is what I do."  Also, you might read some biographies of polymaths.  They will give you inspiration and insights.


  
  Is there something called "overly curious" 
  


Curiosity is only excessive if it distracts from the focus necessary to develop depth in your specialty, or gets in the way of getting meaningful work done (courses passed, papers published, etc.).  PhD is about depth, so if your curiosity keeps you hopping from question to question where you develop only a superficial understanding, then, yes, it is excessive.