Lack of resources/sex is responsible for a majority of conflict. I also think that religious and racist attitudes can lead to conflict. Even if you feel that racist attitudes stem from lack of resources (blaming another ethnic group for your problems) this does not explain racist attitude and behaviors by ruling parties against ethnic minorities.
No, I think that there are more reasons for war and conflicts than just sex and lack of resources. I think that while those two reasons can be a reason to some wars, I think there are a lot more reasons that nations and countries go to war and have conflicts.
No, I do not believe that a lack of resources and/or sex can explain all conflicts, because there have been a lot of conflicts that have been caused by other things. The Muslims are not lacking for resources, but they still came to the United States and flew some planes into buildings. Hate can cause conflicts, too.
I do not believe all problems/conflicts can be explained by a lack of sex and/or a lack of resources. Conflicts come about for a variety of reasons and circumstances. It is rarely caused by one single problem. I think assuming something such as this is quite infantile and I think it is an attempt to overlook the real problems.
Resources have often been integral in conflict, and one should consider sex a resource, as it is scarce and in demand. However, conflict has arisen from other easily identified factors, such as jealousy, pettiness, and irrationality. While conflict often takes place in order to secure scarce goods, other factors relating to personalities should not be overlooked.